JPH0586262A - Casting resin composition and insulating spacer using the same composition - Google Patents

Abstract

PURPOSE:To obtain a composition providing insulating spacers having high heat resistance and crack resistance and low dielectric constant by blending a composition comprising a specific epoxy compound and a curing agent, etc., with a granular or fibrous filler. CONSTITUTION:(A) A composition comprising (i) 99-60 pts.wt. epoxy compound containing plural epoxy groups in the molecule, (ii) 140 pts.wt. modified low- molecular weight polyolefin obtained by subjecting a low-molecular weight polyolefin to graft copolymerization with one or more unsaturated carboxylic acids (anhydride or ester) and (iii) a curing agent for epoxy resin is blended with (B) a granular or fibrous filler composed of alumina having preferably 1.0-20mum average particle diameter alone or plural fillers to give the objective composition.

Description

Detailed Description of the Invention

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting resin composition suitable as an insulating material or a structural material for electric equipment and parts, and particularly to a gas-insulated switchgear, a pipeline air transmission device, or The present invention relates to a casting resin composition most suitable for use as an insulating spacer used in other electric devices and an insulating spacer using the same.

[0003]

2. Description of the Related Art In recent years, a gas-insulated switchgear and a pipeline air transmitter have been widely used as a switchgear and a power transmitter for a high voltage circuit that constitutes a substation. In these gas-insulated switchgear and pipeline air transmission device, an insulating spacer is used to insulate and support the high-voltage conductor in the grounded metal container.

Examples of such insulating spacers include Japanese Patent Publication No. 54-44106 and Japanese Patent Laid-Open No. 55-1.
A technique as disclosed in Japanese Patent No. 55512 has been proposed.
That is, in the insulating spacers disclosed in these publications, the high-voltage conductor is supported by the insulating spacer body made of synthetic resin such as epoxy resin, and the insulating spacer is fixed to the ground metal container at the flange portion of the insulating spacer. Is formed with a metal flange portion. Also,
The SF ₆ gas sealed in the grounded metal container tends to deteriorate its insulating performance when the electric field is non-uniform.
As a countermeasure, a ground shield is integrally embedded around the high-voltage conductor, and the potential is secured by the metal flange portion.

FIG. 1 is a vertical sectional view showing an example of a cone-shaped insulating spacer having the above-mentioned general structure. As shown in FIG. 1, the high voltage conductors 1a and 1b are
Insulated and supported by a cone-shaped insulating spacer 4 in a grounded metal container 3 in which an insulating gas 2 such as SF ₆ gas is sealed. A current-carrying member 4a for joining adjacent high-voltage conductors 1a and 1b is integrally cast on the insulating spacer 4. On the other hand, the grounding metal container 3 is provided with a connecting flange 5 for connecting the grounding metal containers 3 adjacent to each other. On the other hand, a metal flange 6 is integrally cast on the outer edge portion of the insulating spacer 4, and the metal flange 6 is sandwiched by the connecting flange 5 formed on the ground metal container 3 and the mounting bolt 7 is attached. The insulating spacer 4 is fixed to the grounded metal container 3 by being fixed by. Further, a conductive ring 8 corresponding to the above-mentioned ground shield is integrally cast in the insulating spacer 4, and the conductive ring 8 is always grounded, so that the ground metal container 3 and the insulating spacer 4 are The electric field at the coupling portion with and is relaxed, and the insulation performance is improved. In the figure, 9 is an O-ring interposed at the connection between the insulating spacer 4 and the grounded metal container 3, and the O-ring 9 provides an airtight seal.

Insulating spacer 4 having the above structure
As an insulating casting material for the main body, an epoxy resin using an acid anhydride as a curing agent is generally used as a base material because of its chemical stability and mechanical strength. In particular, as an insulating spacer for a gas-insulated switchgear using SF ₆ gas as an insulating medium, (1) material cost is reduced, (2) elastic modulus is increased to increase product rigidity,
For the purpose of (3) improving the mechanical strength, (4) lowering the coefficient of linear expansion to improve the moldability, etc., the above epoxy resin is generally filled with alumina. ..

On the other hand, for the purpose of downsizing the equipment, the allowable value of the temperature rise of the conductive portion of the conductor is increasing, and it is required to improve the heat resistance (high temperature creep property) of the insulating spacer resin. In order to improve heat resistance (high temperature creep property), a method of raising the glass transition temperature of the resin is generally used, but the brittleness of the resin increases as the glass transition temperature rises. Since the thermal stress based on the difference in the linear expansion coefficient of (3) increases, the crack resistance is significantly reduced. On the other hand, as a method of improving the impact resistance of the resin itself, an epoxy resin is modified or blended with an impact resistance-imparting component such as a modified low molecular weight polyolefin, polybutadiene, or silicon rubber described in International Publication No. W087 / 07900. There are methods such as. However, these conventional methods have not been sufficiently studied as structural materials for large high-voltage components such as insulating spacers. There is room for development.

Therefore, in an insulating spacer used in a gas insulated switchgear using SF ₆ gas or the like as an insulating medium or a pipeline air transmission device, an inorganic filler such as alumina is highly filled in the resin. By making the linear expansion coefficient close to that of the embedded metal member to reduce the thermal stress, maintain the glass transition temperature of the resin, and improve the crack resistance while maintaining the heat resistance (high temperature creep property). Is commonly used.

[0009]

However, as described above, in the insulating spacer used for the gas-insulated switchgear, the pipeline air transmission device, etc., the inorganic filler such as alumina is highly filled in the resin. In this case, the following drawbacks have occurred. That is, since the dielectric constant of alumina is large, high filling of alumina increases the dielectric constant of resin,
It was disadvantageous in insulation design. Also, the high filling of alumina is
Since the modulus of elasticity of the resin is increased, there is a drawback in that the strain at the time of breakage becomes small in terms of mechanical properties, and the breakage value at the product stage decreases. Further, high filling of alumina increases the resin viscosity at the time of casting, resulting in a short pot life and a decrease in workability. In addition, since the conventional resin does not have a large adhesive force with the embedded metal member, it is generally necessary to perform a primer treatment on the metal member in order to secure a sufficient adhesive force. That also reduced workability.

As described above, in the conventional insulating spacer, high heat resistance (high-temperature creep property) and crack resistance are achieved at a high level by filling the resin with alumina at a high level. However, such conventional techniques have problems such as an increase in dielectric constant, a decrease in mechanical strength at the product stage, and a decrease in workability.

The above-mentioned various problems are not limited to the insulating spacers used in the gas-insulated switchgear, the pipeline air-power transmission device, etc., but various large-sized products made of the same resin composition are used. The same was also true for other insulating materials or structural materials for electric devices and parts such as cast materials and semiconductor encapsulation materials.

The present invention has been proposed in order to solve the problems of the prior art as described above, and a first object of the invention is to provide insulation for use in a gas-insulated switchgear, a pipeline air transmission device, and the like. By improving the casting resin composition in the spacer, both heat resistance (high temperature creep characteristics) and crack resistance are achieved at a high level, while the dielectric constant is low and mechanical properties at the product stage are high. An object of the present invention is to provide an excellent insulating spacer having excellent strength and good workability.

The second object of the present invention is suitable not only as an insulating spacer, but also as an insulating material or structural material for other large-sized castings and other electric devices and parts such as semiconductor sealing materials. Such an excellent casting resin composition is to be provided.

[Constitution of the Invention]

[0015]

The casting resin composition according to the present invention comprises (A) 99 to 60 parts by weight of an epoxy compound having two or more epoxy groups in at least one molecule;
(B) Modified low molecular weight polyolefins 1 to 4 obtained by graft-copolymerizing at least one unsaturated carboxylic acid derivative selected from the group consisting of unsaturated carboxylic acids, acid anhydrides and esters thereof with low molecular weight polyolefins
It is characterized in that a particulate or fibrous filler is blended alone or in combination with a composition containing 0 part by weight; (C) a curing agent for epoxy resin.

The insulating spacer according to the present invention is used in a gas-insulated switchgear, a pipeline air-transmitting device, or other electric equipment, and insulates and supports a high-voltage conductor in a metal container or between other members. In the insulating spacer for performing the insulation, the casting resin composition is used.

Further, as the casting resin composition of the present invention, it is possible to specifically use various components as shown below.

First, as the epoxy compound (A) used in the present invention, any epoxy compound having at least two epoxy groups in at least one molecule can be appropriately used, and the kind thereof is limited. However, examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, alicyclic epoxy resin, hydrogenated bisphenol A type epoxy resin, and heterocyclic epoxy resin such as triglycidyl isocyanate and hydantoin epoxy. These compounds are used alone or as a mixture of two or more kinds.

Next, the modified low molecular weight polyolefin (B)
As a low molecular weight polyolefin used as a raw material of
Ethylene component 30-75 mol% and C3-C20 α-
It is preferable to use an ethylene-based random copolymer (ethylene / propylene random copolymer) having an olefin component of 25 to 70 mol% and a number average molecular weight of 400 to 2000. In particular, the ethylene / propylene ratio is preferably about 50/50 in view of the balance between heat resistance and mechanical properties of the insulating spacer (or other cured product).

Further, modified low molecular weight polyolefin (B)
As the unsaturated carboxylic acid derivative components 5 to 20 selected from the group consisting of unsaturated carboxylic acids having 3 to 10 carbon atoms and their acid anhydrides and esters thereof, relative to 100 parts by weight of the low molecular weight polyolefin. It is desirable to use a material obtained by graft-copolymerizing parts by weight. In this case, the unsaturated carboxylic acid is preferably maleic anhydride, acrylic acid or the like.

The epoxy compound (A) and the modified low molecular weight polyolefin (B) as described above are physically mixed before reacting with the curing agent (C) for epoxy resin, or the modified low molecular weight polyolefin. The acid anhydride ring and the carboxyl group which are the graft polymerization components in (B) are used by previously reacting with the epoxy group of the epoxy compound (A). In this case, the modified low molecular weight polyolefin (B)
If the blending amount is less than 1 part by weight, the effect of improving the characteristics is not sufficient, and if blending over 40 parts by weight, the viscosity increases greatly, which is not preferable in terms of workability. For this reason, in the present invention, as described above, the modified low molecular weight polyolefin (B) is used in an amount of 1 to 40 parts by weight.

Further, the curing agent (C) for epoxy resin used in the present invention is generally an aliphatic or aromatic acid anhydride, carboxylic acid, amine or phenol which is used as a compound for epoxy resin. The classes can be used alone or in the form of a mixture of two or more kinds. In particular, phthalic anhydride, hexahydrophthalic anhydride, methyl acid hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, nadic acid anhydride, methyl nadic acid anhydride, etc., which have a long pot life and generate little heat during curing, Acid anhydrides are desirable, and among them, phthalic anhydride and methyl nadic acid anhydride are advantageous from the viewpoint of workability because they have a long pot life and quick curing, and their cured product properties are similar to those of other cured products. Better than when using agents. The compounding amount of these curing agents for epoxy resin is preferably in the range of 0.7 to 0.9 equivalent to 1 equivalent of epoxy, and when less than this range, insulating spacer (or other curing) Environment resistance such as heat resistance and moisture resistance of a product) is significantly reduced. Further, if the blending amount is more than this range, the chemical heat resistance and the electrical characteristics of the insulating spacer (or other cured product) will be deteriorated.

On the other hand, in the casting resin composition of the present invention, any kind of filler can be blended as long as the workability is not impaired. For example, as a particulate filler, silica, alumina, talc, calcium carbonate, aluminum hydroxide, kaolin, clay, dolomite, mica powder, silicon carbide, glass powder, carbon, graphite, barium sulfate, titanium dioxide, boron nitride, Silicon nitride or the like can be used. Further, as the fibrous filler,
Warlastonite, potassium titanate whiskers, glass fiber, alumina fiber, silicon carbide fiber, boron fiber, carbon fiber, aramid fiber, phenol fiber,
Metal whiskers can be used. These fillers are used alone or as a mixture of two or more kinds. Among them, alumina is the epoxy resin of the present invention, that is,
It has excellent adhesiveness with an epoxy resin modified with a modified low molecular weight polyolefin (B), and in particular, by using alumina having an average particle size of 1.0 to 20 μm as a filler, SF ₆ decomposition gas resistance, An insulating spacer (or other cured product) having excellent thermal conductivity and mechanical strength can be obtained. The total blending amount of this filler is 3 with respect to the entire composition.
It is desirable to mix as needed in an amount of 5% by volume or more and 55% by volume or less. This is because the phase blending amount of the filler is 35% by volume.
If it does not satisfy the requirement, it becomes impossible to obtain the elastic modulus required for the structure, and when the total amount of the fillers exceeds 55% by volume, the viscosity increases remarkably, which makes casting work difficult. It depends on the reason.

The casting resin composition of the present invention may contain various additives as required. For example, additives such as flame retardants, antioxidants, pigments and dyes can be added.

[0025]

By using the casting resin composition of the present invention having the above composition, it is possible to easily produce an excellent insulating spacer by the usual method for producing an insulating spacer. That is, the epoxy compound (A) and the modified low molecular weight polyolefin (B) are sufficiently vacuum-mixed with a filler by a conventional method using a universal mixer, and then mixed with a curing agent (C) for epoxy resin. However, it can be easily manufactured by a manufacturing method similar to the case of using a normal insulating spacer casting epoxy resin, such as injecting into a mold.

Further, the casting resin composition of the present invention has the above-mentioned composition, so that the heat resistance can be improved while keeping the filling rate of the inorganic filler having a large dielectric constant and elastic modulus such as alumina low. Property (high temperature creep property) and crack resistance can be compatible at a high level. Therefore, the heat resistance (high temperature creep property) and the crack resistance are compatible with each other at a high level, the dielectric constant can be reduced, and the mechanical strength at the product stage can be improved. In this case, since the pot life can be lengthened, there is also an advantage that workability can be improved.

Furthermore, when the casting resin composition of the present invention is used to form an insulating spacer, since the adhesive strength with the embedded metal member is large, the insulation reliability can be improved. In this case, it is possible to omit the primer treatment of the metal member that is generally performed to secure the adhesive force between the casting resin composition and the embedded metal member, which contributes to further improvement in workability. it can.

The casting resin composition of the present invention is suitable not only as an insulating spacer but also as an insulating material or structural material for various large castings and other electric devices and parts such as semiconductor sealing materials. Therefore, similarly, excellent characteristics can be exhibited.

[0029]

EXAMPLES Examples of insulating spacers using the casting resin composition of the present invention and comparative examples according to the prior art will be shown below, and the insulating spacers of these examples and comparative examples will be evaluated by comparison. The function and effect of the present invention will be described in more detail. The insulating spacers prototyped in all the examples and the comparative examples have a cone shape as shown in FIG. 1 and have the same structure in which a current-carrying member 4a made of aluminum is arranged in the center, and the diameter is 650 mm and the main body is The insulating spacer 4 (model spacer) having a dimension of the resin portion having a maximum thickness of 90 mm was used.

Example 1 As a modified low molecular weight polyolefin (B), a maleic anhydride-grafted ethylene propylene random copolymer (maleic anhydride-containing 10% by weight, ethylene / propylene composition ratio = 50/50, number average molecular weight 900) was used. Used as the epoxy compound (A),
Bisphenol A, bisphenol A type epoxy resin,
Using O-cresol novolac type epoxy resin,
A modified epoxy resin having an epoxy equivalent of 270 prepared by condensation reaction of these modified low molecular weight polyolefin (B) and epoxy compound (A) was obtained. Next, 100 parts by weight of this modified epoxy resin having an epoxy equivalent of 270, 45 parts by weight of phthalic anhydride as a curing agent (C) for epoxy resin, and particulate alumina as a filler (average particle diameter 12 μm)
280 parts by weight are blended and 110-120 with a universal mixer.
Vacuum mixing was carried out at 0 ° C. to obtain a resin composition. Further, this resin composition was cast in a mold preheated to 120 ° C. and cured under the conditions of primary curing 120 ° C. × 15 hours and secondary curing 150 ° C. × 15 hours to prepare a model spacer. In this example, the primer treatment was not applied to the aluminum current-carrying member arranged in the center of the model spacer.

Example 2 As the modified low molecular weight polyolefin (B), a maleic anhydride grafted ethylene propylene random copolymer (maleic anhydride content 10% by weight, ethylene / propylene composition ratio = 50/50, number average molecular weight 900) was used. Used as the epoxy compound (A),
Modified low molecular weight polyolefin (B) using bisphenol A and bisphenol A type epoxy resin
To obtain a modified epoxy resin having an epoxy equivalent of 390, which was prepared by a condensation reaction between the epoxy compound and the epoxy compound (A). Next, this modified epoxy resin 100 having an epoxy equivalent of 390
30 parts by weight of phthalic anhydride as a curing agent (C) for epoxy resin and 250 parts by weight of particulate alumina (average particle diameter 12 μm) as a filler are mixed in 1 part by weight, and mixed with a universal mixer 1
It vacuum-mixed at 10-120 degreeC and obtained the resin composition. Furthermore, this resin composition was cast in a mold preheated to 120 ° C., primary curing 120 ° C. × 10 hours, secondary curing 130 ° C.
It was cured under the condition of × 15 hours to prepare a model spacer. In this example, the primer treatment was not applied to the aluminum current-carrying member arranged in the center of the model spacer.

(Example 3) The resin composition and curing conditions were exactly the same as in Example 2 to prepare a model spacer.
However, in this example, the primer treatment was applied to the aluminum current-carrying member arranged in the center of the model spacer.

On the other hand, in contrast to the examples according to the present invention as described above, a casting resin composition generally used as a large-sized casting insulator resin was adopted as a comparative example according to the prior art, A model spacer was produced under the following conditions.

Comparative Example 1 As an epoxy resin, a bisphenol A type epoxy resin (epoxy equivalent 390) 85
Using 15 parts by weight and alicyclic epoxy resin,
35 parts by weight of phthalic anhydride as a curing agent and 320 parts by weight of particulate alumina (average particle size 12 μm) as a filler were mixed in a universal mixer at 110 to 120 ° C. under vacuum to obtain a resin composition. Then, this resin composition is treated at 120 ° C.
Then, it was cast in a preheated mold and cured under conditions of primary curing of 120 ° C. × 15 hours and secondary curing of 150 ° C. × 15 hours to prepare a model spacer. In this comparative example,
A primer treatment was applied to the aluminum current-carrying member arranged in the center of the model spacer in the same manner as in Example 3.

Comparative Example 2 Bisphenol A type epoxy resin (epoxy equivalent 390) 10 was used as the epoxy resin.
0 parts by weight, 30 parts by weight of phthalic anhydride as a curing agent, and particulate alumina as a filler (average particle size 12 μm)
Add 300 parts by weight and use a universal mixer for 110-120
Vacuum mixing was carried out at 0 ° C. to obtain a resin composition. Then, this resin composition was cast in a mold preheated to 120 ° C. and cured under the conditions of primary curing 120 ° C. × 15 hours and secondary curing 130 ° C. × 15 hours to prepare a model spacer. In this comparative example, a primer treatment was applied to the aluminum current-carrying member arranged in the center of the model spacer in the same manner as in Example 3.

(Comparative Example 3) The resin composition and the curing conditions were exactly the same as in Comparative Example 2 to prepare a model spacer.
However, in this comparative example, the primer treatment was not applied to the aluminum current-carrying member arranged in the center of the model spacer.

Table 1 shows the evaluation results of the model spacers produced in Examples 1 to 3 and Comparative Examples 1 to 3. Of the various characteristics shown in Table 1, the fracture stress is that the internal pressure is gradually applied to the model spacer incorporated in the predetermined test device,
It was calculated from the maximum value of the surface strain with load pressure measured by a strain gauge. The starting point of the breakage was the interface between the current-carrying member and the resin in any model spacer. On the other hand, the glass transition temperature Tg was determined from the change in specific heat of a sample cut out from a model spacer, measured by a differential scanning calorimeter (DSC). As the thermal shock resistance, the crack resistance index of each resin used by the M20 flat washer method is shown.

[0038]

[Table 1]

As is clear from Table 1 above, in the examples of the present invention, both the glass transition temperature and the thermal shock resistance were superior to the comparative examples of the prior art, and therefore the heat resistance ( High temperature creep characteristics) and high level of crack resistance. Moreover, it is apparent that the examples of the present invention have a lower relative permittivity and excellent fracture stress at the product stage, as compared with the comparative examples according to the prior art.

Further, in Comparative Examples 2 and 3 according to the prior art, there is a difference in fracture stress due to the presence or absence of the primer treatment, whereas in Examples 2 and 3 according to the present invention, the primer treatment is performed. A stable high fracture stress is obtained regardless of the presence or absence of This demonstrates that when an insulating spacer is manufactured using the casting resin composition of the present invention, the primer treatment is unnecessary and the workability can be improved by that amount.

The casting resin composition according to the present invention is
The present invention is not limited to the above-mentioned embodiment, and as described in the column of means for solving the problem, various kinds of materials can be selectively used, and even in that case, it is excellent as in the above-mentioned embodiment. It is possible to obtain the action effect. Further, the use of the casting resin composition according to the present invention is not limited to the insulating spacer, and as described above, it can be used to insulate various large castings and other electric devices and parts such as semiconductor sealing materials. It is also suitable as a material or a structural material.

[0042]

As described above, the casting resin composition of the present invention is a novel resin composition obtained by mixing a certain modified low molecular weight polyolefin with an epoxy resin. When an insulating spacer is manufactured using a resin composition for molding, it has better heat resistance (high temperature creep property) and crack resistance than an insulating spacer using a conventional general casting epoxy resin composition. It is possible to provide an excellent insulating spacer having a high level of compatibility, a low dielectric constant, an excellent mechanical strength in a product stage, and a good workability.

Further, the casting resin composition of the present invention is suitable not only as an insulating spacer but also as an insulating material or structural material for various large-sized castings and other electric devices and parts such as semiconductor sealing materials. Is.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a cone-shaped insulating spacer having a general configuration as an application example of an insulating spacer according to the present invention.

[Explanation of symbols]

 1a, 1b High-voltage conductor 2 Insulation gas 3 Ground metal container 4 Insulation spacer 4a Conductive member 5 Connecting flange 6 Metal flange 7 Mounting bolt 8 Conductive ring 9 O-ring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Ichikawa 21-4 Kansei-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Chemical Co., Ltd. Irifune Plant (72) Inventor Yasushi Kanesashi 21 Kansei-cho, Tsurumi-ku, Yokohama-shi, Kanagawa -4 Toshiba Chemical Co., Ltd. Irifune Office

Claims (2)

[Claims] 1. A compound selected from the group consisting of (A) 99 to 60 parts by weight of an epoxy compound having two or more epoxy groups in at least one molecule, (B) an unsaturated carboxylic acid, an acid anhydride and esters thereof. Modified low molecular weight polyolefins 1 to 4 obtained by graft-copolymerizing at least one unsaturated carboxylic acid derivative with a low molecular weight polyolefin
A casting resin composition comprising 0 part by weight of (C) a curing agent for an epoxy resin and a particulate or fibrous filler alone or in combination. 2. A gas insulated switchgear, a pipeline air transmission device,
In an insulating spacer used for other electric equipment to insulate and support a high-voltage conductor in a metal container or to insulate other members, the casting resin composition according to claim 1 is used. An insulating spacer characterized in that